ok simple(or at least simpler than custom meshes) go to http://www.gimp.org/ its a free, no risk download for a powerful tool. play around with it and get the hang of it(there are tuts on their site) then make your texes and save them as .PCX files. open up UnrealEd and go to the Texture browser. click File>Import. browse until you find your texture(s) and hit OK. a little menu will open up. DON'T TOUCH ANYTHING except the package group and texture names. you can make up your own group name(it will make a new file), but then you will need to send the texpackage for the map to work. Or you can put Mylevel in the group name and the textures will be saved in the map file. the downside of this is that you cannot use the textures in other maps. Hope this helps!

Im doing this too maybe we can work on it together. I am creating a death trooper map if you havent read the book it is about infected storm troopers that kill anything. I made it kind of like the ras prosecutor level where you dont know what happened but you see dead bodies eveywhere.